Conditions and factors of humus formation in soils of mountain and foothill

On the basis of information on the climatic factor, the intensity of humus formation in the soil was estimated. It was revealed that as the transition from the plain to the foothills and low mountains due to changes in atmospheric precipitation and hydrothermal regime, the period of biological activity (PBA) of the soil increases from the plain to the mountains. The balance of annual radiation in the foothill plain is 47 kcal/cm2, in the high-mountain belt - 53 kcal/cm2. As the transition from the plain to the mountainous part of the relief, an increase in soil PBA was revealed and, in accordance with this, the content and reserves of humus, as well as labile humic substances in the humus composition, increase. By the type of humus, light gray soils are humate-fulvate and fulvate; typical, dark gray soils and mountain brown soils, fulvate-humate; light brown meadow-steppe soils, and humate. It also provides information on the energy reserves of humus for the considered soils. The correlations between the indicators of PBA and humus for horizon “A” in the studied soils were calculated.

К оценке гумусного состояния и ферментативной активности почв Дальневосточного морского заповедника

Indicators of humus state and catalase activity were determined in the soils of the Far Eastern marine reserve. The average humus content was exposed for the dark humus burozem and the dark humus soil, formed on buried burozem. The distribution of humus in the profile is estimated as gradually decreasing, the humus reserves in the 20 cm layer are characterized as very high and high. Variation of the typical humus composition and humification index differs in the studied soils. "Free" fractions predominate in the composition of humic acids, their proportion reaching high and very high values. The surface horizons of soils are characterized by poor and very poor catalase enrichment. The morphological shape of the profile and the parameters of the humus state of the studied soils of the far Eastern marine reserve confirm the previously obtained data on climate changes and ocean transgression in the South-Western part of the Pacific coast of the region in the Holocene.

CALCIUM IN SOIL HUMUS OF WEST-SIBERIAN TRANSECT

The paper analyzes the behavior of one of the main components of humus (humic acids - calcium system) depending on the participation of calcium in the biological cycle of substances. The role of calcium in the formation of ecological stability of humic systems is shown, which largely determines the environmentally sustainable agriculture. It is shown that the changeable calcium amounts to no more than a half of its total content in humus horizon of automorphic zonal soils. Within the limits of the transect, the participation of calcium in binding of humic and fulvic acids is distributed according to their content in humus composition. Additional assessment of exchangeable calcium content to be determined by nontraditional method showed the same geographic regularity of its distribution in the soils of the transect as in the case of distribution of the main characteristics of humus.

Humus acids as reserve of water-soluble organic matter in irrigated chernozems of Near-Ob are

It has been shown the role of carbon of dissolved organic matter (C DOM) in humus composition of irrigated chernozems as well as participation of humus substances proper in the formation of DOM. It has been found out that in chernozem long-term irrigated with weakly alkaline water the yield of C DOM is reliably higher than in nonirrigated soil when used even ordinary water extraction. It accounts for 53 and 40 mg l–1 respectively. It is attributed to the fact that because of influence of irrigative water the pH range became wider to some extent and alkalinity of soil medium became stronger and consequently the solubility of DOM increased. It has been noted that that the same tendency that is decrease is observed in depthwise distribution of humus and C DOM. As it should be expected, in irrigated soil processed with irrigative water the content of C DOM is somewhat higher (by 7–10 mg l–1) in the studied part of the profile as a whole. At the same time the relative role of C DOM in humus composition increases with increasing pH, up to 3 % of total organic soil carbon. It has been examined the interaction of irrigative water free of DOM with preparations of humus acids extracted from soil. Drown coloration of irrigative water is evidence of separation of DOM from humus acids. Moreover, the yield of C DOM proved to be three times higher in case of irrigative water than distilled one and accounted 120 and 350 mg l–1 respectively. This comparative experiment is an evidence of the fact that humus acids can be served as a source of DOM, especially in the event if more accessible organic matter is not available. Thus, long-term irrigation of chernozems in case of unsatisfactory application of organic fertilizers leads not only to biological and irrigational humus losses but also humus losses by way of transformation of humus acids into DOM

Soil Organic Carbon Accumulation under Different Forms of Organo-Mineral Fertilizers and Methods of Their Application on Ukrainian Black Soil

<p>Soil organic carbon management is a key element in solving such urgent global-scale challenges as overcoming degradation of soils and mitigating climate change. Organic fertilizers application has a significant potential for sequestering C in soils, but their efficiency depends on decomposition characteristics. Firstly, it noted the dependence of resynthesis of humic compounds in a soil on a quality of organic inputs, secondly - a need for zonal approach to fertilizers production based on amphiphile properties of macromolecules.</p><p>The present study was conducted in long-term field experiment on black soil in Forrest-Steppe zone of Ukraine. The technology of production of organo-mineral fertilizers (OMFs) was based on the regulated processing of livestock waste with mineral components to stabilize it with hydrophobic bonds. OMFs in amorphous and granular form were compared in case of broadcast and band method of incorporation. The dose of OMF input was equivalent 350 C kg ha<sup>-1</sup> and 80 N, 80 P, 80 K kg ha<sup>-1</sup>. Organic carbon content in soil was determined by Turin method. Different organic matter fractions were isolated: humic acids (HA), fulvic acids (FA), and humin.</p><p>The soil C accumulation rates in OMF treatment was by 15 % higher than in manure treatment and up to 70 % higher than in chemical fertilizer treatment, respectively. The soil C accumulation was strongly influenced by the form of OMF and method of their application. The highest TOC level was found over band application of amorphous OMF, accumulating 6.2 t C ha<sup>–1</sup> yr<sup>–1 </sup>in 0-20 cm soil layer. Lower efficiency of broadcast incorporation OMFs could be explained by more intensive mineralization due to higher aeration. Taking into account the effect of OMFs on C stock an advantage of amorphous form versus granulated OMF with similar composition was proven. Black soil on control plot (without fertilization) had almost equal ratio between HA, FA and humin in humus composition. The content of humic compound increased in all treatments. Applying OMF significantly increased HA content in black soil compared to applying mineral fertilizer. OMFs application promoted the increase of the degree of condensation of organic matter. The highest HA/FA was found under the effect of broadcast incorporation OMF. That means that low molecular weight compounds were rapidly degraded while more resistant to mineralization HA were formed in soil. There was no significant difference in humus composition between amorphous and granulated OMF.</p>

Organic matter transformation in post-agrogenic soils of the Middle Taiga zone

Objective. The purpose is to study the organic matter transformation in Podzols from the middle taiga zone.Methods. The study materials are arable lands from the central regions of the Komi Republic. These lands are not agriculturally used since the early 90-ies of the former century. The soil analyses are done according to the common methods.Results. The study allows for the humus profile structure of Podzols along with the following successive stages as meadow idle land young forest dwarf shrub-green moss spruce forest. It also describes the mechanisms of post-agrogenic humus transformation in agricultural sod Podzols due to the self­ restoring succession.Conclusion. Initially, the post-agrogenic soils normally repeat agrozems by characteristics. The upper soil part forms a thin grey-humus (sod) horizon. It contains large amounts of humus, exchangeable cations, and nutrition elements. The specific synthesis and destruction processes of humic substances at the meadow idle land stage change the qualitative humus composition. In contrast with arable lands, the humus composition is dominated with fulvic acids as being best appropriate to the concerned bioclimatic zone. The humuc-fulvic humus composition holds only in the upper old-arable soil part of the meadow idle land. The appearance of pioneer tree species increases the dominating position of FAs and the Cha/Cfa ratio resembles that for forest soil. The organic matter is poor in nitrogen compounds, especially at the young forest stage. By the C/N ratio, the post-agrogenic soils also gradually get close to naturally formed soils under virgin forest.

Effects of Returning Granular Corn Straw on Soil Humus Composition and Humic Acid Structure Characteristics in Saline-Alkali Soil

Returning straw plays an important role in protecting the environment and maintaining the sustainable development of agriculture. In this research, we explored the effects of returning granular corn straw on soil humus composition and humic acid structural characteristics in a typical saline-alkali soil. This study was conducted in Jilin province. A randomized block design consisting of nine plots with three treatments in three replicates was used for this study. The treatments were granular corn straw (GS), coarse corn straw (CS), and control (CK). The results show that treatments GS and CS both increased the contents of soil humus and its components in the soil compared to CK. However, treatment GS recorded the highest significant increase in soil humus carbon (HEC), fulvic acid carbon (FAC), and humic acid carbon (HAC) by 17.59%, 8.32%, and 26.51%, respectively. Comparing the two straw treatments, it was found that the relative intensities of treatment GS at 2920 and 2850 cm−1 were higher than treatment CS by 1.58% and 72.49%, respectively. The relative intensities of treatment GS at 1720 cm−1 and 1620 cm −1 were lower than treatment CS by 52.2% and 30.43%, respectively. Moreover, an analysis of soil humic acid (HA) through an infrared spectrum, fluorescence spectrum, and principal components analysis (PCA) showed that the application of straw makes the structure of HA aliphatic, simple, and younger, and also promotes the continuous renewal of humus. In this study, the application of granular corn straw effectively improved the soil humus content and humic acid structural characteristics and is thus highly recommended.